Meningococcal Meningitis

Overview

Meningitis is an infection of the thin lining that surrounds the brain and spinal cord called the meninges. Viral and bacterial infections are the most common cause but bacterial meningitis is much more serious due to its rapid onset and poses a significant risk of death. Meningococcal meningitis is a bacterial form of meningitis.

The use of the MenAfriVac® vaccine to prevent meningitis A epidemics in the African Region is one of the greatest vaccination success stories in public health history and highlights what partners can accomplish when unified by a compelling cause.

In 2014, the MenAfriVac® campaigns reached more than 63 million people with remarkable success. In all, over 217 million people between one and 29 years of age have benefited from the vaccine since 2010.

This unprecedented achievement is due to the overall availability, safety and effectiveness of the vaccine. MenAfriVac® is incredibly stable – being the first vaccine to be used with the controlled temperature chain (CTC) approach. This has allowed its transport and storage for as long as 4 days in ambient temperatures up to 40°C.

The World Health Organization (WHO) now recommends the conjugate meningitis A vaccine MenAfriVac® to be introduced in routine immunization schedules in sub-Saharan Africa. This recommendation ensures that infants are protected against meningitis and population-wide immunity is maintained.

Disease Outbreak

Related Health Topics

Factsheet

Key Facts

Meningococcal meningitis is a bacterial form of meningitis, a serious infection of the thin lining that surrounds the brain and spinal cord.

The extended meningitis belt of sub-Saharan Africa, stretching from Senegal in the west to Ethiopia in the east (26 countries), has the highest rates of the disease.

Before 2010 and the mass preventive immunization campaigns, Group A meningococcus accounted for an estimated 80–85% of all cases in the meningitis belt, with epidemics occurring at intervals of 7–14 years. Since then, the proportion of the A serogroup has declined dramatically.

Several vaccines are available to control the disease: a meningococcal A conjugate vaccine, C conjugate vaccines, tetravalent A, C, Y and W conjugate vaccines and meningococcal polysaccharide vaccines.

As of June 2015, over 220 million persons aged 1 to 29 years have received meningococcal A conjugate vaccine in 15 countries of the African belt.

Meningococcal meningitis is a bacterial form of meningitis, a serious infection of the meninges that affects the brain membrane. It can cause severe brain damage and is fatal in 50% of cases if untreated.

Several different bacteria can cause meningitis. Neisseria meningitidis is the one with the potential to cause large epidemics. There are 12 serogroups of N. meningitidis that have been identified, 6 of which (A, B, C, W, X and Y) can cause epidemics. Geographic distribution and epidemic potential differ according to serogroup.

Highly contagious meningitis outbreaks continue in African countries

Meningitis outbreaks continue to be an enormous public health threat in the African Region. The outbreak in Nigeria is of utmost concern but Ghana and Niger are also experiencing meningitis outbreaks.

The outbreak in Nigeria started on 19 January 2015 in Aliero, Local Government Area (LGA) of Kebbi State and the World Health Organization (WHO) was notified on 16 February 2015. Cases have been reported in 26 LGAs of three States, Kebbi, Sokoto and Zamfara. Of confirmed cases, Neisseria meningitidis serogroup C is the type identified.

A national task force in Nigeria has been activated with the support of WHO and partners to manage the outbreak of bacterial meningitis. The Nigeria Centre for Disease Control (NCDC) of the Federal Ministry of Health of Nigeria notified WHO of 1380 cases, including 83 deaths as of 5 April 2015.

In Ghana, the meningitis outbreak is ongoing in Upper West Region. As of 5 April 2015, 205 cases with 23 deaths have been reported in the country. No causative microorganisms have been isolated so far and lab results are pending.

Increasing numbers of meningitis cases have also been reported in Niger since February 2015. The main serotypes that have been identified include the W135, C and pneumococcus. As of 5 April 2015, 461 cases and 62 deaths have been notified with a case fatality rate of 15.3%. Dosso and Niamey are the most affected regions.

Meningitis is an infection of the thin lining that surrounds the brain and spinal cord called the meninges. Viral and bacterial infections are the most common cause but bacterial meningitis is much more serious due to its rapid onset and it poses a significant risk of death.

Neisseria meningitidis can be carried in the throat and sometimes, for reasons not fully understood, can overwhelm the body's defenses allowing infection to spread through the bloodstream to the brain. It is believed that 10% to 20% of the population carries Neisseria meningitidis in their throat at any given time but the carriage rate may be higher in epidemic situations.

The most common symptoms of meningitis are stiff neck, high fever, sensitivity to light, confusion, headaches and vomiting. Bacterial meningitis can also result in mental retardation, deafness, epilepsy, or necrosis leading to limb amputation.

Meningococcal disease is potentially fatal and should always be viewed as a medical emergency. Even when the disease is diagnosed early and adequate treatment is started, 5% to 10% of patients die, typically within 24 to 48 hours after the onset of symptoms. It is important to know which type of bacteria is causing the meningitis because antibiotics can prevent some types from spreading and infecting other people.

Appropriate antibiotic treatment must be started as soon as possible. A range of antibiotics can treat the infection, including penicillin, ampicillin, chloramphenicol and ceftriaxone. Under epidemic conditions in Africa in areas with limited health infrastructure and resources, ceftriaxone is the drug of choice.

There are many vaccines against meningitidis. The conjugate meningitis A vaccine MenAfriVac® is recommended to protect people against serotype A, the most common type, in order to maintain wide-spread immunity and avert epidemics.

In October 2014, the WHO Strategic Advisory Group of Experts (SAGE) on immunization concluded that a one-dose schedule of MenAfriVac® is recommended. In 2014, the MenAfriVac® campaigns reached more than 63 million people with remarkable success. Nigeria conducted mass campaigns in all States at risk, including Kebbi state.

WHO and partners, including Médecins Sans Frontières and UNICEF, are closely monitoring the situation, and providing support to the government of Nigeria for the implementation of a mass vaccination campaign and other emergency control measures. The International Coordinating Group (ICG) on Vaccine Provision for Epidemic Meningitis Control has released 204 850 doses of vaccine, with the support of the GAVI Alliance, as well as 5000 antibiotic vials to respond to the outbreak. Case management and social mobilization activities are also ongoing.

To further facilitate meningitis control efforts, the upcoming African Vaccination Week (AVW) that is commemorated from 24 to 30 April will provide an opportunity for affected countries to strengthen immunization services and systems through advocacy, social mobilization, education and communication tools and activities.

WHO does not recommend any travel or trade restriction to Nigeria or other affected countries based on the current information available.

The bacteria are transmitted from person-to-person through droplets of respiratory or throat secretions from carriers. Close and prolonged contact – such as kissing, sneezing or coughing on someone, or living in close quarters (such as a dormitory, sharing eating or drinking utensils) with an infected person (a carrier) – facilitates the spread of the disease. The average incubation period is 4 days, but can range between 2 and 10 days.

Neisseria meningitidis only infects humans; there is no animal reservoir. The bacteria can be carried in the throat and sometimes, for reasons not fully understood, can overwhelm the body's defenses allowing infection to spread through the bloodstream to the brain. It is believed that 10% to 20% of the population carries Neisseria meningitidis in their throat at any given time. However, the carriage rate may be higher in epidemic situations.

Symptoms

The most common symptoms are a stiff neck, high fever, sensitivity to light, confusion, headaches and vomiting. Even when the disease is diagnosed early and adequate treatment is started, 5% to 10% of patients die, typically within 24 to 48 hours after the onset of symptoms. Bacterial meningitis may result in brain damage, hearing loss or a learning disability in 10% to 20% of survivors. A less common but even more severe (often fatal) form of meningococcal disease is meningococcal septicaemia, which is characterized by a haemorrhagic rash and rapid circulatory collapse.

Diagnosis

Initial diagnosis of meningococcal meningitis can be made by clinical examination followed by a lumbar puncture showing a purulent spinal fluid. The bacteria can sometimes be seen in microscopic examinations of the spinal fluid. The diagnosis is supported or confirmed by growing the bacteria from specimens of spinal fluid or blood, by agglutination tests or by polymerase chain reaction (PCR). The identification of the serogroups and susceptibility testing to antibiotics are important to define control measures.

Treatment

Meningococcal disease is potentially fatal and should always be viewed as a medical emergency. Admission to a hospital or health centre is necessary, although isolation of the patient is not necessary. Appropriate antibiotic treatment must be started as soon as possible, ideally after the lumbar puncture has been carried out if such a puncture can be performed immediately. If treatment is started prior to the lumbar puncture it may be difficult to grow the bacteria from the spinal fluid and confirm the diagnosis.

A range of antibiotics can treat the infection, including penicillin, ampicillin, chloramphenicol and ceftriaxone. Under epidemic conditions in Africa in areas with limited health infrastructure and resources, ceftriaxone is the drug of choice.

Prevention

There are 3 types of vaccines available.

Polysaccharide vaccines have been available to prevent the disease for over 30 years. Meningococcal polysaccharide vaccines are available in either bivalent (groups A and C), trivalent (groups A, C and W), or tetravalent (groups A, C, Y and W) forms to control the disease.

For group B, polysaccharide vaccines cannot be developed, due to antigenic mimicry with polysaccharide in human neurologic tissues. The first vaccine against NmB, made from a combination of 4 protein components, was released in 2014.

Since 1999, meningococcal conjugate vaccines against group C have been available and widely used. Tetravalent A, C, Y and W conjugate vaccines have been licensed since 2005 for use in children and adults in Canada, the United States of America, and Europe.

The extended meningitis belt of sub-Saharan Africa, stretching from Senegal in the west to Ethiopia in the east (26 countries), has the highest rates of the disease. The 26 countries include: Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Democratic Republic of Congo, Eritrea, Ethiopia, The Gambia, Ghana, Guinea, Guinea Bissau, Kenya, Mali, Mauritania, Niger, Nigeria, Rwanda, Senegal, South Sudan, Sudan, Tanzania, Togo and Uganda. The risk of meningococcal meningitis epidemics differs within and among these 26 countries.

In December 2010, a new meningococcal A conjugate vaccine was introduced nationwide in Burkina Faso, and in selected regions of Mali and Niger (the remaining regions were covered in 2011), targeting persons 1 to 29 years of age. As of June 2015, 220 million persons have been vaccinated with this vaccine in 16 countries (Benin, Burkina Faso, Cameroon, Chad, Côte d’Ivoire, Ethiopia, The Gambia, Ghana, Guinea, Mali, Mauritania, Niger, Nigeria, Senegal, Sudan, and Togo).

The MenA conjugate vaccine has several advantages over existing polysaccharide vaccines:

it induces a higher and more sustainable immune response against group A meningococcus;

it reduces the carriage of the bacteria in the throat and thus its transmission;

it is expected to confer long-term protection not only for those who receive the vaccine, but on family members and others who would otherwise have been exposed to meningitis;

it is available at a lower price than other meningococcal vaccines (around 0.50 USD per dose, other meningococcal vaccine prices range from 2.50 USD to 117.00 USD per dose); and

it is expected to be particularly effective in protecting children under two years of age, who do not respond to conventional polysaccharide vaccines.

In addition, its thermostability allows for a use under Controlled Temperature Chain (CTC) conditions. More than 2 million persons in 4 countries have been vaccinated without ice use at the vaccination site.

It is planned that all 26 African countries considered at risk for meningitis epidemics and targeted by this vaccine introduction programme will have introduced this vaccine by 2016. High coverage of the target age group of 1–29 years is expected to eliminate meningococcal A epidemics from this region of Africa.

Outbreak Trends

Meningococcal meningitis occurs in small clusters throughout the world with seasonal variation and accounts for a variable proportion of epidemic bacterial meningitis.

The largest burden of meningococcal disease occurs in an area of sub-Saharan Africa known as the meningitis belt, which stretches from Senegal in the west to Ethiopia in the east. During the dry season between December to June, dust winds, cold nights and upper respiratory tract infections combine to damage the nasopharyngeal mucosa, increasing the risk of meningococcal disease. At the same time, transmission of N. meningitidis may be facilitated by overcrowded housing and by large population displacements at the regional level due to pilgrimages and traditional markets. This combination of factors explains the large epidemics which occur during the dry season in the meningitis belt.

Following the successful roll-out of the MenA conjugate vaccine, epidemics due to N. meningitidis serogroup A are disappearing, but other meningococcal serogroups such as NmW, NmX and NmC still cause epidemics albeit at a lower frequency and smaller size.

WHO response

WHO promotes a strategy comprising epidemic preparedness, prevention and response. Preparedness focuses on surveillance, from case detection to investigation and laboratory confirmation. Prevention consists of vaccinating all 1-29 year-olds in the African meningitis belt with the MenA conjugate vaccine. WHO regularly provides technical support at the field level to countries facing epidemics. Epidemic response consists of prompt and appropriate case management with reactive mass vaccination of populations not already protected through vaccination. Meningitis epidemics in the African meningitis belt constitute an enormous public health burden. WHO is committed to eliminating meningococcal disease.

The Meningitis Vaccine Project - frequently asked questions

The bacteria are transmitted from person-to-person through droplets of respiratory or throat secretions from carriers. Close and prolonged contact – such as kissing, sneezing or coughing on someone, or living in close quarters (such as a dormitory, sharing eating or drinking utensils) with an infected person (a carrier) – facilitates the spread of the disease. The average incubation period is 4 days, but can range between 2 and 10 days.

Neisseria meningitidis only infects humans; there is no animal reservoir. The bacteria can be carried in the throat and sometimes, for reasons not fully understood, can overwhelm the body's defenses allowing infection to spread through the bloodstream to the brain. It is believed that 10% to 20% of the population carries Neisseria meningitidis in their throat at any given time. However, the carriage rate may be higher in epidemic situations.